1. Field of the Invention
The present invention relates to an apparatus for stacking a predetermined number of sheet members that are successively charged via a feed system in a stacking position, an apparatus for measuring dimensions of sheet members, and an apparatus for and a method of marking sheet members.
2. Description of the Related Art
There have been used packaged products each comprising a stack of sheet members, e.g., sheet-like photosensitive members such as X-ray films, which are packaged by a package film as a light shielding member. For producing such packaged products, it is customary to stack a predetermined number of sheet-like photosensitive members with a stacking device before the sheet-like photosensitive members are delivered to a next process such as a packaging process or the like.
In the stacking device, sheet-like photosensitive members are successively supplied to a stacking position by a feed system such as a belt conveyor or the like, and then successively dropped onto an lining cardboard, a product tray, or a stacking bottom plate. For example, Japanese laid-open patent publication No. 4-209158 discloses a sheet-like member stacking apparatus which has a sheet holding means for vertically stacking and holding a plurality of sheet-like members in a given stacking position, a sheet supply means for supplying sheet-like members substantially horizontally from a position near the stacking position to a position over the stacking position, and dropping the sheet-like members to the stacking position, and a suction means for pulling downwardly a rear end of the sheet supply means.
The suction means generates an air flow for lowering the rear end of a sheet-like member that is dropped to the stacking position by the sheet supply means. Since the air flow quickly lowers the rear end of the sheet-like member that is dropped by the sheet supply means, a succeeding sheet-like member does not hit the preceding sheet-like member. Thus, successive sheet-like members can smoothly and efficiently be stacked in the stacking position.
With the conventional sheet-like member stacking apparatus, sheet members cannot be delivered or expelled to a front stopper for limiting front end positions thereof if the speed for stacking sheet members is set to a relatively low value. A first sheet member to be stacked is liable to impinge upon an lining cardboard, a product tray, or a stacking bottom plate that is placed in the stacking position, making it difficult to stack a desired number of sheet members stably in the stacking position and also tending to cause damage to the sheet members which suffer a reduction in product quality.
There are known apparatus including an electronic flash lamp and an optical sensor for measuring dimensions of a sheet member that is being fed. These known apparatus include an apparatus for applying light from an electronic flash lamp toward a sheet member, detecting light reflected from the sheet member with a camera, and detecting the position of ends of the sheet to measure dimensions of the sheet member (see Japanese laid-open patent publication No. 4-9605, for example) and an apparatus having an electronic flash lamp and a sensor that are disposed one on each side of a sheet member feed path, the sensor detecting a position where light from the electronic flash lamp is blocked by a sheet member to measure dimensions of the sheet member (see Japanese laid-open patent publications Nos. 5-52526 and 6-147836, for example).
There has been a demand for the measurement of dimensions of a sheet-like photosensitive member with an apparatus having an electronic flash lamp and an optical sensor as described above. One problem with the apparatus used for measuring dimensions of a sheet-like photosensitive member is that when light from the electronic flash lamp is applied to the sheet-like photosensitive member, the sheet-like photosensitive member is apt to be fogged. Consequently, it has been difficult to use the apparatus for the purpose of measuring dimensions of a sheet-like photosensitive member.
Sheet-like photosensitive members are marked by a marking device with a latent image of a manufacturing lot number representing manufacturing information such as a processed sequence and an ISO sensitivity value representing the sensitivity of the sheet-like photosensitive member. The marked information is turned into a visible image when the sheet-like photosensitive member, such as an X-ray film, is processed by a developing process. The marked information becomes effective for the user if the X-ray film is defective, for example.
The marking device uses LEDs as light sources for emitting light with several colors as a means for marking desired letters or the like on X-ray films. For example, green light emitted from a green LED and red light emitted from a red LED are mixed into yellow light, which is applied to an X-ray film to mark the X-ray film with desired letters or the like. Each of the LEDs is connected to an LED driver for energizing the LED for light emission.
Since the marking device uses a plurality of LEDs, it also requires as many LED drivers as the number of LEDs, and hence necessarily becomes large in size. In addition, the marking device needs a complex control system for the LED drivers. The complex control system cannot easily be maintained and managed, and tends to increase the equipment cost of the marking device.